JP2003314684A - Method of protecting torque converter for automatic transmission from overheating, and driving slip control device equipped with protecting function - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a torque converter protecting function of a driving slip control device so as to decrease engine torque when actually required for protecting a torque converter for an automatic transmission. <P>SOLUTION: In the method of protecting the torque converter for the automatic transmission from overheating during driving slip, an energy loss converted in the torque converter or a numeric value in proportion to the energy loss is calculated, and engine torque is decreased when the energy loss and the numeric value in proportion to the energy loss exceeds a predetermined threshold. The driving slip control device comprising the above-mentioned protecting function is provided with a device calculating the energy loss and the numeric value in proportion to the energy loss and decreasing the engine torque when the energy loss and the numeric value in proportion to the energy loss exceeds the predetermined threshold. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for protecting a torque converter of an automatic transmission of a vehicle from overheating, and a drive slip control device having such converter protection function.

[0002]

2. Description of the Related Art When starting on a road (μ-split road) having different static friction coefficients on the left side and the right side of a vehicle, when a relatively small drive torque is set, the wheels (low μ roadside wheel) is rotated. When the wheel speed on the low μ road side exceeds the set slip threshold,
A drive slip control (ASR) device acts on the running motion of the vehicle and brakes the slipping wheels.

At this time, the braking torque applied to the wheels on the low μ road side is transmitted to the non-slip vehicle side wheels (high μ road side wheels) via the differential device, and can be used there for moving the vehicle forward.

[0004] In such control, the engine torque in the brake is converted into heat by braking the slipping wheel. In the case of a vehicle with an automatic transmission, this results in particular that the engine torque transmitted in the torque converter of the automatic transmission is converted into thermal energy (excluding the torque acting on the brake),
This can damage the torque converter or transmission in a relatively short time.

In the starting process under the conditions of μ-split road, the braking resistance torque and rolling resistance torque of the vehicle, and the vehicle and the towed vehicle, especially in the case of an automobile having a heavy load or having a towed vehicle, Since the slope output torque acting is greater than the engine torque provided by the engine, a situation may arise in which the vehicle cannot continue to run despite the maximum drive torque. In such a situation, the load becomes excessive and the torque converter correspondingly rapidly overheats.

The drive slip control devices known from the prior art are therefore activated in the control state “select high” and at vehicle speeds of less than 5 km / h for a starting process on the μ-split road and for a predetermined time (eg, It includes a converter or transmission protection function implemented using a simple time counter that forces a switch to "select low" after 15 seconds).

The "select high" state of the ASR serves to achieve as high a traction force as possible, and is characterized by a high drive wheel slip threshold and a relatively high applied engine torque. On the other hand, the "select low" state plays a role in achieving the highest possible vehicle stability, and the slip threshold is adjusted with extremely high sensitivity.
Corresponding to this, the engine torque is low.

A drawback of the known protection function is that the ASR provides a fixed (time-controlled) switching independent of the actual load of the torque converter. This allows a vehicle that moves slowly forward with slippery drive wheels to be controlled to full load speed just before reaching a slippery road, even though the temperature reached in the torque converter has not yet demanded it. There are cases.

[0009]

SUMMARY OF THE INVENTION It is therefore an object of the invention to provide a drive slip control converter so that the engine torque is reduced when it is actually needed to protect the automatic transmission torque converter. It is to improve the protection function.

[0010]

According to the invention, in a method for protecting a torque converter of an automatic transmission from overheating during drive slip control, the energy loss converted in the torque converter or proportional to it. When a numerical value is calculated and the energy loss or a numerical value proportional thereto is above a predetermined threshold value, the engine torque is reduced.

Further, according to the present invention, in the drive slip control device having the function of protecting the torque converter of the automatic transmission from overheating during the drive slip control, the loss energy converted in the torque converter or And a device for reducing the engine torque when the converter energy loss or a value proportional thereto exceeds a predetermined threshold value.

The basic concept of the present invention is to calculate the loss energy converted by the torque converter, or a numerical value proportional thereto, and when the loss energy or a numerical value proportional thereto exceeds a predetermined threshold value. The engine torque is reduced. Energy loss, or a number proportional to this, measures the temperature in the torque converter,
This reduces the load on the converter only when the converter temperature requires it.

In the preferred embodiment of the invention, the torque balance is set via the drive torque and the delay torque acting in the vehicle, from which the converter torque loss is determined. The torque loss of the converter is preferably integrated over time, thereby calculating a dissipation value converted in the torque converter and thus a reference value which is a measure of the converter temperature.

When calculating the loss energy converted in the torque converter or the proportional value, the heat dissipation of the torque converter is preferably included. An ASR that is in the "select high" state at the beginning of the startup process preferably
When the energy loss converted in the torque converter, or a value proportional thereto, exceeds a predetermined threshold value, the "select low" state is entered.

[0015]

Next, the present invention will be described in detail based on the embodiments. When the vehicle is started under the condition of the μ-split road, the wheels on the slippery road side are in a slip state due to the engine torque adjusted by the driver. AS
R detects this and controls the corresponding brake pressure on the low μ roadside wheels. Since the vehicle does not start, the applied engine torque is converted into heat in the torque converter and the brake and into acceleration torque in the connecting rod. In this case, the following relational expressions apply.

[0016]

[Equation 1] However, M _MOT : Given engine torque M _BREMS : Braking torque converted in the brake M _{WANDLERVERLUST} : Loss torque heating the converter M _WBR : Acceleration resistance of connecting rod Rotational torque Acceleration of connecting rod continues only for a short time .
After that, it becomes fixed. That is, the angular acceleration becomes zero, and the acceleration resistance rotation torque M _WBR also becomes zero. In the fixed state, converter torque loss M
_{WANDLER VERLUST} is as _follows .

[0017]

[Equation 2] The brake pressure P _BREMS supplied by the ASR is as _follows .

[0018]

[Equation 3] However, C = conversion constant [Nm / bar].

The acceleration resistance rotation torque M _WBR of the connecting rod is _calculated as _follows .

[0020]

[Equation 4] However, J: inertia torque [kgm ² ] ω: angular acceleration [1 / s ² ] The engine speed and the wheel speed are known, and the individual inertia torque J of the connecting rod is also known.

In order to calculate the loss energy converted in the converter, the converter loss torque M
_{WANDLERVERLUST} is integrated over time. At that time,
The energy dissipation due to convection and thermal radiation, which especially serves to reduce the temperature, is preferably included. This is applied in the iterative calculation (index t) below.

[0022]

[Equation 5] However, dM _KONVEKTION : Converter limit torque M set as the applicable parameter threshold
_{When WANDLER_GRENZ} is exceeded, the operating state of ASR switches from "select high" to "select low". That is, the engine is controlled with extremely high sensitivity.

In another embodiment of the invention, a temperature model may be used to determine the temperature of the torque converter. Here, the temperature model is a computer model showing the thermal state of the torque converter under various driving conditions and braking conditions. The temperature model may, for example, store the converter torque loss as an initial value and possibly also include heat dissipation.

The ASR preferably switches from "select high" to "select low" when the temperature determined by the temperature model exceeds a predetermined threshold. Embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

FIG. 1 shows in the form of a flow chart the course of the method for protecting the torque converter from overheating.
In that case, in the first step 1, the loss energy M _{WANDLERVERLUST} converted in the torque converter, or a numerical value proportional thereto, is calculated, and this numerical value is compared with a predetermined threshold value sw in step 2.

When the loss energy converted in the torque converter is equal to or larger than the threshold value sw (M _{WANDLER VERLUST}
> sw), in step 3, the engine torque is reduced,
In other cases, the actual engine torque is retained.

FIG. 2 shows a drive slip control device 4 provided with a calculation device 5 for calculating the energy loss converted in the torque converter or a numerical value proportional thereto. In this case, the actual braking torque M _BREMS and the actual engine torque M _MOT are transmitted to the drive slip control device 4. As described above, when the converter energy loss or the proportional numerical value exceeds the predetermined threshold value, the engine torque M _MOT is reduced.

[Brief description of drawings]

FIG. 1 is a flow chart illustrating a method of protecting a torque converter from overheating according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of a drive slip control device.

[Explanation of symbols]

1-3 method steps 4 Drive slip control (ASR) device 5 calculator

Continued front page    F term (reference) 3G093 AA05 BA08 BA17 CB14 DA01                       DB11 EA02 FA07 FB02                 3J053 BB13 CA00 CB22 DA01 DA07                       DA08 DA14 EA01 FA03

Claims (6)

[Claims] 1. A method for protecting a torque converter of an automatic transmission from overheating during drive slip control, in which loss energy converted in the torque converter or a numerical value proportional thereto is calculated, and the loss energy or A method of protecting a torque converter of an automatic transmission from overheating, wherein engine torque is reduced when a value proportional to this exceeds a predetermined threshold value. 2. A method as claimed in claim 1, characterized in that the engine torque balance is set via the drive torque and the retard torque acting in the vehicle, from which the converter torque loss is determined. 3. The method of claim 2, wherein the converter loss torque is integrated over time. 4. The heat dissipation of the torque converter is taken into account when calculating the energy loss converted in the torque converter or a numerical value proportional thereto. The method described. 5. The drive slip control is switched from a "select high" state to a "select low" state when the loss energy converted in the torque converter or a value proportional to the loss energy exceeds a threshold value. The method according to any one of claims 1 to 4, characterized in that 6. In a drive slip control device having a function of protecting a torque converter of an automatic transmission from overheating during drive slip control, a loss energy converted in the torque converter or a numerical value proportional thereto is calculated. However, the drive slip control device is provided with a device that reduces the engine torque when the converter energy loss or a numerical value proportional thereto exceeds a predetermined threshold value.